Central lateral line pathways are being studied by axonal degeneration, radioautographic and horseradish peroxidase methods in the smooth dogfish shark (Mustelus canis) and clear-nosed skate (Raja eglanteria). Emphasis is being given to the differential efferent projections of the anterior lateral line lobe (nucleus dorsalis), posterior lateral line lobe (mucleus medialis), and auricle of the cerebellum. Mechanical lesions will be placed in the above receptive areas for lateral line neurons and following post-operative survival periods of appoximately 4 weeks, the brains will be fixed by perfusion and frozen sections of the brain stems process by the Fink-Heimer technic to depict degenerating axons and terminals. Complimentary experiments will be done by injecting small amounts of minus 3H proline or horseradish peroxidase into central lateral line centers and brain stem sections processed to show anterograde and retrograde degeneration respectively. BIBLIOGRAPHIC REFERENCE: McCready, P.J. and R.L. Boord. 1976. The topography of the superficial roots and ganglia of the anterior lateral line nerve of the smooth dogfish, Mustelus canis. J.Morph., 150:527-538.